Linear motors are well known in the art and used in many different industries. For example, linear motor systems are used in wire bonding machines to provide high speed linear motion along various axes. For example, in certain wire bonding machines, linear motors are used to provide precise high speed motion along an x-axis and a y-axis of the machine.
One problem well known in the field of linear motors is cogging. For example, cogging forces in linear iron-core synchronous/brushless DC motors is undesirable because it tends to act as a disturbance to the current/force loop of a servo system, thereby compromising servo system performance.
In linear motors including coil assemblies (e.g., laminated armatures including teeth configured to be wound with coils), one method of reducing cogging forces has been related to the design of the end teeth of the coil assembly. For example, U.S. Pat. No. 4,912,746 to Oishi reduces the unit volume of the teeth at the axial ends of the armature core by cutting out a section of the end teeth. In another example, U.S. Pat. No. 5,910,691 to Wavre provides end teeth 78, 80 having a first segment 84 adjacent a second sloped segment 86.
Therefore, while prior art attempts at reducing cogging effects in linear motors by specialized design of the end teeth of an armature are known, increased pressure for reduced cogging in linear motors continues in the industry.
Thus, it would be desirable to provide a linear motor system with reduced cogging.